A radio frequency (RF) block is designed to support many frequency bandwidths in a mobile communication system. In particular, a variable capacitor having a different capacitance for each frequency bandwidth should be used as a capacitor used in a filter having a direct relation to a frequency bandwidth. Furthermore, a voltage controlled oscillator (VCO), which is one element in an RF block, adjusts a voltage applied to a variable capacitor to vary the capacitance thereof, and changes a resonance frequency thereby. In this way, the variable capacitor is a very important device for a tunable filter or a VCO for the RF block.